This invention relates to a carburettor, by which I mean a device which defines respective inlets for air and fuel and a common outlet for a mixture of the air and fuel, which device causes mixing of the fuel and air when in use. The invention is concerned primarily with carburettors for internal combustion engines.
A pressure differential which causes flow of fuel into the carburettor through the fuel inlet thereof and into a stream of air flowing through the carburettor may be established by a venturi effect on the air stream, by the action of gravity on the fuel, by the action of a pump on the fuel or by a combination of these. In a case where the fuel is caused to flow into the carburettor by a pump, the pump may operate continuously. Alternatively, the pump may operate intermittently to inject into the air stream at a predetermined time a predetermined volume of fuel or to inject fuel into the air stream for a period of predetermined duration.